Evidence-informed health policy making contributes to improved health outcomes by strengthening health systems. In addition, health policy decisions should take into consideration the needs and priorities of users of healthcare services. However, little research has been done to find best ways to facilitate evidence-informed and participatory health policymaking, particularly in low- and middle-income countries. This thesis is written based on three studies done in Ethiopia to fill this knowledge gap. In the first study, we examined whether, how and under what conditions evidence was used and service-users participated during the agenda-setting and policy formulation phases of selected policies in the ‘prevention of mother-to-child transmission of HIV’ program in Ethiopia using a multiple-case study design. In the second study, we identified strategies to facilitate evidence-informed health policy making using an online survey. In the third study, we identified strategies to facilitate participatory health policy making using a combined paper-based and Internet-based Delphi approach. The thesis does not have direct theoretical contribution. However, it will draw on two theoretical frameworks, namely Kingdon’s framework and the 3I+E framework. and use them in a setting from where they were originally developed. This thesis has two substantive and three methodological contributions. Substantively, the first study provides empirical evidence about the current practice of evidence-informed and participatory health policy making in a low-income, ‘revolutionary’ democratic country (Ethiopia). In addition, the studies have identified strategies to concretize the constitutional and policy provisions for evidence-informed and participatory health policy making in Ethiopia. The thesis has the following three methodological contributions. First, the studies explored the use of Kingdon’s multiple-streams framework and the 3I+E framework in predicting factors influencing agenda-setting and policy formulation phases, respectively, and in explaining the use of research evidence in informing these two phases in a ‘revolutionary’ democratic country where they have not previously been used. Second, the thesis has shown that paper-based and Internet-based Delphi could be combined in contexts with limited resources. Third, the thesis has demonstrated the possibility of training service-users as ‘peer’ researchers to collect and analyze data to inform their participation and maximize their contribution in surveys, forming a pyramid of participation. / Thesis / Doctor of Philosophy (PhD) / Evidence-informed health policy making can contribute to improved health outcomes by strengthening health systems. In addition, health policy decisions ultimately affect users of healthcare services. Thus, such decisions should take into consideration their needs and priorities. However, little research has been done to find best ways to facilitate evidence-informed and participatory health policymaking, particularly in low- and middle-income countries. This thesis is written based on three studies done in Ethiopia. In the first study, we examined whether, how and under what conditions evidence was used and service-users participated in the ‘prevention of mother-to-child transmission of HIV’ program in Ethiopia. In the second and third studies, we identified strategies to facilitate evidence-informed and participatory health policy making. In addition, we explored the possibility of combining Internet- and paper-based methods for consensus-building among policymakers, program managers, researchers, healthcare providers and service-users in settings with limited resources.